This invention relates to the manufacture of nonwoven pile articles, especially of the type wherein a backing is bonded to free ends of an assembly of pile yarns or fibers. In a particular sense, the invention is directed to apparatus and procedures for producing such articles on a substantial scale in an effectively continuous, automated manner.
Seamless pile articles of large size, e.g. carpets, are produced commercially as elongated webs that may have a width ranging up to twelve or even fifteen feet or more. Desirably, such pile materials should be made more or less continuously by automated apparatus having high production speeds, with economy in consumption of pile fibers, capability of forming varied and intricate patterns, and selectively in control of pile density.
In present-day commercial techniques for making pile articles of extended size, the individual pile-forming yarns or fibers (herein termed pile elements) are commonly bent into loops which are passed through or otherwise secured to a backing. The looped portions of the pile elements, which represent a substantial proportion of the total pile fiber used, do not contribute to the appearance or density of the pile because they are attached to the backing. Consequently, the described looping techniques involve uneconomical consumption of pile fiber. Owing in particular to the necessity of forming thousands of individual pile element loops, commercially available machines for producing pile articles by looping techniques tend to have slow production speeds and to be subject to frequent breakdowns or other interruptions of operation.
It has also heretofore been proposed to make a pile article by forming an assembly of "straight" (i.e. non-looped), substantially aligned pile fibers, and bonding a backing to the free ends of the assembled fibers. The elimination of loops in these so-called bonding techniques represents a substantial saving in pile fiber, as compared with looping techniques, for production of a pile of given depth and density; in addition, the mechanical problems of loop forming are avoided.
Serious disadvantages have nevertheless attended efforts to adapt bonding techniques to large-scale commercial production, especially in respect to the provision of means and methods for forming, handling and maintaining the assembly of aligned fibers prior to application of the backing. In particular, it has heretofore been supposed that the assembly of fibers must be continuously positively maintained in a compacted condition, as by lateral compression, until the backing is applied, for prevention of misalignment of the fibers. This requirement has precluded attainment of desired flexibility or selectively in control of pile density, and has necessitated use of inconveniently complex mechanical expedients for handling the fiber assembly. Such procedure effectively precludes use of twisted yarn (which is already very dense and compact) as pile elements, because the requisite compaction of the pile elements would, in the case of twisted yarn, produce a pile of unacceptably high density wherein the individual elements could not be caused to bloom as in conventional twisted-yarn piles.
Other problems have been encountered in attempting to provide for cutting and feeding pile fibers to the assembly. For example, in one known type of bonding apparatus, a continuous strip of long, aligned fibers (equal in width to the pile article to be made) is progressively fed to a pile-forming locality where it is sheared to provide successive thin rows of cut pile fibers, these rows being individually advanced into compacted assembly with previously cut rows of fibers for subsequent application of a backing thereto. Apart from the difficulty of achieving uniform longitudinal feed of elongated aligned fibers, the strip feeding arrangement prevents pattern variations along the length of the produced pile article, i.e. unless the feed of fibers is repeatedly interrupted for change in color of fibers being fed. Since the strip of fibers must be very thin in order to be effectively uniformly sheared, each incremental addition to the pile fiber assembly (i.e. the thickness of each successively advanced row of cut fibers) is correspondingly small, resulting in slow production speeds. Moreover, it is difficult to handle a very long continuous row of cut fibers, as required for production of a wide pile article owing to the fact that each row of cut fibers extends over the full width of the produced article.
Alternatively it has been proposed to prepare relatively small groups of aligned cut fibers which are adhered together in some removable manner, as by freezing in water; and, after a plurality of these groups or blocks of adhered fibers are assembled together and secured to a backing, to remove the initial fiber-adhering substance. This technique involves problems, e.g. in supplying and removing an adhering fluid, as well as increased cost, and again, does not permit desired control of pile density because the fibers remain adherent to each other until after they are bonded to the backing.
Applicant's prior U.S. Pat. No. 3,499,807, discloses a method of making non-woven pile articles by forming a plurality of pile units each comprising an array of substantially aligned pile yarns or fibers laterally compressed within a surrounding removable sleeve. The pile units, which may be radially symmetrical, are positioned (e.g. by hand) on an assembly surface in a desired arrangement to constitute a complete pile assembly. Thereafter, the sleeves are removed, and a backing is applied to the free ends of the assembled fibers. This method, while capable of forming satisfactory pile articles on a piecework basis, requires substantial manual labor and thus, insofar as described in the aforementioned patent, does not constitute a commercially competitive procedure for large-scale mass production of pile articles such as extended carpeting and the like.